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ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.
Sec. Bacteria and Host
Volume 14 - 2024 | doi: 10.3389/fcimb.2024.1530178

Corynebacteria from the respiratory microbiota modulate inflammatory responses and associate with a reduced pneumococcal burden in the lungs

Provisionally accepted
Caroline Bergenfelz Caroline Bergenfelz *Phuong Do Phuong Do Liv Larsson Liv Larsson Kasper Malmborn Kasper Malmborn Anders P Hakansson Anders P Hakansson
  • Lund University, Lund, Sweden

The final, formatted version of the article will be published soon.

    Background: Certain species from the normal respiratory tract microbiota have recently been proposed to positively influence human health. Corynebacterium propinquum and C. pseudodiphtheriticum (Corynebacteria) are two Gram-positive species that frequently colonize the upper respiratory tract and strongly associate with a reduced incidence of respiratory tract infections. The specific role of Corynebacteria during respiratory health and disease is, however, largely uncharacterized. Method: Respiratory tract epithelial cells NCI-H292 and BALB/cByJ mice were inoculated with Corynebacteria (C. propinquum 2018M3 and 2019M4, and C. pseudodiphtheriticum 2019M8 and 2020M12) alone or with subsequent challenge with Streptococcus pneumoniae (pneumococci). The inflammatory response and the bacterial burden of both species over time were determined by Western blot, luciferase assay, cytokine bead array, flow cytometry and viable plate counts on blood agar plates. Results: Clinical isolates of Corynebacteria were well tolerated by human cells and mice. Corynebacteria induced a transient inflammatory response during healthy conditions in the absence of known pathogens. Pre-exposure or nasal priming with Corynebacteria did not affect subsequent acquisition of pneumococci but were associated with a modulated inflammatory response in vitro and in vivo as well as with a reduced pneumococcal burden in the respiratory tract of mice. This indicates that the presence of C. propinquum or C. pseudodiphtheriticum may protect against severe pneumococcal infections. Conclusions: In this study, we delineate the role of Corynebacteria from the normal microbiota that epidemiologically associate with respiratory health. We show that the presence of Corynebacteria modulates the inflammatory response to pneumococci and associate with faster decrease in pneumococcal burden, primarily in the lower respiratory tract. Our data indicate that Corynebacteria has potential to protect against severe pneumococcal infections.

    Keywords: Corynebacteria, microbiota, respiratory tract, Pneumonia, Streptococcus pneumoniae, Inflammation

    Received: 18 Nov 2024; Accepted: 30 Dec 2024.

    Copyright: © 2024 Bergenfelz, Do, Larsson, Malmborn and Hakansson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Caroline Bergenfelz, Lund University, Lund, Sweden

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.